Abstract:

A restraining system for a motor vehicle with a seat belt retractor that
accommodates the one end of a seatbelt component, which has a tightening
device having a belt shaft and a drive cable connected to the belt shaft,
in which a sleeve (26) that enlarges the outer circumference of the shaft
element (25) is slid onto one end of the shaft element (25) and is
axially and radially fixed to the shaft element (25), while the wall
thickness of the sleeve (26) is dimensioned in such a way that the drive
radius of the shaft element (25) and a reduction in speed of the
tightening drive is provided as compared with a cable wrapped onto the
belt shaft.

Claims:

1. A restraining system for a motor vehicle comprising a seat belt
retractor for fixing a seatbelt component, which has a belt shaft element
and a pretensioner device attached to the belt shaft element having a
drive cable which is tensioned by a piston upon actuation, a sleeve that
enlarges the outer circumference of the belt shaft element is slid on one
end of the belt shaft element and is axially and radially fixed to the
shaft element, wherein the wall thickness of the sleeve provides a drive
radius of the cable wrapped on the sleeve which is greater than the
radius of the belt shaft element.

2. The restraining system according to claim 1, wherein the belt shaft
element is configured as a hollow shaft with a locking element arranged
in the interior of the shaft element, and the sleeve is slid on the end
of the shaft element that accommodates the locking element, which is
mounted in a retractor housing leg, and has an opening, which is flush
with a passage opening of the shaft element of the locking element.

3. The restraining system according to claim 1, wherein the drive cable
passes through the sleeve and is mounted on the belt shaft element.

4. The restraining system according to claim 1, the drive strand cable is
fixed on the sleeve.

5. The restraining system according to claim 1, wherein the drive strand
cable is jointly mounted on the belt shaft element and on the sleeve.

6. The restraining system according to claim 2, wherein the locking
element is supported with a gearing of the housing leg on a nose-shaped
edge region of the passage opening of the shaft element.

7. The restraining system according to claim 2, wherein the locking
element, when it is engaged, is supported with a gearing of the housing
leg on an edge region of the opening formed in the sleeve, which is
configured as a nose.

8. The restraining system according to claim 2, wherein the locking
element, when it is engaged, is supported with a gearing of the housing
leg on an edge region of the passage opening of the shaft element as well
as on an opening formed in the sleeve, which is configured as a nose.

9. The restraining system, according to claim 1, wherein the connection of
sleeve and the shaft element is provided by means of at least one stamped
projection, with are oriented towards the interior of the sleeve in order
to engage into an associated recesses of the shaft element.

10. The restraining system according to claim 9, wherein at least one
projection of the sleeve is inclined in the axial direction of the shaft
element.

11. The restraining system according to claim 9, wherein two projections
are arranged with an opposite oriented inclination.

12. The restraining system according to claim 9, wherein a multitude of
recesses and projections are provided distributed around the
circumference of the shaft element and the sleeve.

13. The restraining system according to claim 2, wherein a retaining
element and the sleeve each having a smooth internal circumference are
slid on the shaft element for axially securing the shaft element on the
housing leg, which lockingly interacts with the locking element as well
as the locking element, when it is pivoted out, is slid on the shaft
element between the retaining element and the sleeve, while the shaft
element has a stop for the axial fixation of the retaining element which
comes to rest between the stop and the housing leg, and the outer sleeve
is further fixed to the shaft element by the cable passing through cable
openings.

14. The restraining system according to claim 13, wherein the stop
provided on the shaft element is formed by stamping the shaft element as
a radial projection of the circumference of the shaft element.

15. The restraining system according to claim 13, wherein the internal
retaining element is configured as a retaining ring, which can be slid on
the shaft element, and the, can be slid on the shaft extension against
the housing leg, while the drive cable is wound on the outer
circumference of the sleeve.

16. The restraining system according to claim 15, wherein the anti-sliding
safety for the sleeve consists of the cable fitting, which is configured
at the end of the drive cable, and which passes through openings in the
sleeve as well as the shaft element.

17. The restraining system according to claim 13, wherein the retaining
elements and the sleeve are provided with an axial facet at their front
ends, which face the housing leg, respectively, in such a way that a
linear installation of the retaining element in its circumferential
direction on the housing leg is obtained.

18. The restraining system according to claim 17, wherein the facet of the
retaining elements or the sleeve bridges the passage opening formed in
the shaft element to allow the passage of the locking element.

19. The restraining system according to claim 1, wherein the pretensioner
device is mounted to a belt buckle.

20. The restraining system according to claim 1, wherein the seat belt
retractor is affixed to an end of the seat belt.

[0002]The invention relates to a retention system for a motor vehicle with
a seat belt retractor accommodating one end of a seatbelt component which
has a belt shaft and a pretensioner device having a drive connection with
the belt shaft.

BACKGROUND OF THE INVENTION

[0003]A restraining system of the aforementioned type is described, for
example, in DE 103 04 943 B3. With the known restraining system, the
associated seat belt retractor is part of an end fitting pretensioner in
which the end of the seat belt to be fixed on the motor vehicle structure
is fixed on the retractor shaft, so that this end of the seatbelt is
wound up on the shaft upon actuation of the pretensioner drive and is
tightened in this way. The locking of the shaft element with the seat
belt retractor housing is undertaken in such a way that the locking
element is arranged in the radial interior of the shaft element, which
has a hollow configuration, and is pretensioned by means of a passage
opening configured in the shaft element by spring action over the outer
circumference of the shaft element until it engages in the associated
gearing of the housing leg that supports the belt shaft. Consequently,
the locking element is in a permanent locking with the seat belt
retractor housing so that the end of the seat belt is correspondingly
fixed and therewith fixedly mounted on the motor vehicle. When the
pretensioner drive is activated, the locking element ratchets away
through the gearing of the housing leg in the corresponding direction of
the belt shaft, while in the event of a rotation of the belt shaft in the
belt withdrawal direction after completing the pretensioning rotation,
the immediate locking of the belt shaft takes place.

[0004]It is an object of the invention to increase the pretensioning force
of a restraining system of the type described above.

[0005]This object, including the advantageous embodiments and further
developments of the invention, is attained with the features of the
present invention described herein.

SUMMARY OF THE INVENTION

[0006]The invention provides in its basic conception to slide a sleeve,
which enlarges the outer circumference of the shaft element in this area
and is immovably axially and radially connected to the shaft element, on
one end of the shaft element, in which the thickness of the wall of the
sleeve is dimensioned in such a way that the drive radius of the shaft
element is enlarged and a reduction in speed of the pretensioner drive is
established as compared with wrapping the pretensioner cable directly
onto the shaft element. Due to the arrangement of the sleeve, the
tightening radius and therewith the tightening force are enlarged when
the diameter of the shaft element, and therefore the winding radius of
the wound-up belt webbing, remain constant because the drive cable is
wound around the sleeve at a greater radial distance with respect to the
central axis of the shaft element.

[0007]According to an exemplary embodiment of the invention, the belt
shaft is configured as a hollow shaft with a locking element arranged in
the interior of the shaft element, as is known from the prior technology
as described by DE 103 04 943 B3, in which the sleeve is slid on the end
that accommodates the locking element and is mounted in the housing leg,
and has an opening that is flush with the passage opening of the shaft
element for the locking element.

[0008]According to exemplary embodiments of the invention, it can be
provided with respect to mounting of the drive cable on the belt shaft,
that the drive cable extends through the sleeve and is mounted on the
shaft element, or that the drive cable is mounted directly on the sleeve.
It can also be provided that the drive cable is mounted both on the shaft
element and the sleeve.

[0009]To the extent that a supporting of the locking element on the shaft
element is to be ensured for transferring load from the belt shaft to the
seat belt retractor housing, the locking element can be supported in the
engaged state with the gearing of the housing leg on an edge region of
the passage opening of the shaft element, which is configured as a nose.

[0010]As an alternative, the locking element can be braced in the engaged
state with the gearing of the housing leg at an edge region of the
opening configured in the sleeve, which is configured as a nose.

[0011]An especially secure force transmission results according to one
embodiment of the invention when the locking element is braced in the
engaged state with the gearing of the housing leg on the edge of the
passage opening of the shaft element as well as the opening configured in
the sleeve, which is configured as a joint nose.

[0012]With regard to the radial and axial fixation of the sleeve on the
shaft element, it can be provided according to an exemplary embodiment of
the invention that the connection of the sleeve and the shaft element is
created by means of projections stamped out of the sleeve radially inward
extending into associated recesses of the shaft element.

[0013]As long as the projections of the sleeve are inclined in axial
direction of the shaft element, it is practical to arrange two
projections with an opposite oriented inclination.

[0014]The force transmission is improved overall as long as, according to
an exemplary embodiment of the invention, a multitude of recesses and
projections are distributed over the circumference of the shaft element
and the sleeve.

[0015]In a further embodiment of the invention, it is provided that two
annular closed retaining elements with a smooth internal circumference
enclosing the housing leg as well as the deflected locking element
between them are slid on the shaft element for axial position securing of
the belt shaft on the housing leg lockingly interacting with the locking
element, in which the shaft element has a stop for the axial fixation of
the internal retaining element, which comes to lie between the stop and
the housing leg, and the outer sleeve lying outwardly against the housing
leg as a further retaining element is fixed using an anti-sliding safety
on the shaft element. The advantage that due to the axial shaft fixing
device, an axial displacement of the belt shaft relative to the retractor
housing is ruled out, especially due to the action of the tightening
device coupled to the belt shaft. An axial shaft fixing device such as
this is basically known from the generic restraining system disclosed in
DE 103 48 461 A1.

[0016]As long as according to an exemplary embodiment of the invention it
is provided that the stop provided on the shaft body is formed by
stamping the shaft element as a radial elevation of the circumference of
the shaft element, the advantage that the stop can be economically
manufactured without an additional component is provided.

[0017]In accordance with a further exemplary embodiment of the invention,
it is provided that the inner retaining element is configured as a
retaining ring which can be slid on the shaft element, and the outer
retaining element is configured as a sleeve which can be slid against the
housing leg on the retaining element, while the drive cable is wound on
the outer circumference of the sleeve. In this case, it can be provided
that the anti-sliding safety for the sleeve consists of a cable
suspension configured at the end of the drive cable, which passes through
the sleeve as well as the shaft element of one opening in each case. The
advantage that the anti-sliding safety is likewise realized without an
additional component is associated with this.

[0018]According to an exemplary embodiment of the invention, it is
provided that the retaining elements are provided in each case at their
front end that faces the housing leg with an axial facet, in such a way
that a linear installation of the retaining element on the housing leg
results. In this way, friction losses due to the rotation of the belt
shaft are minimized. It can moreover be provided that the facet of the
retaining elements in each case bridges the opening configured in the
shaft element for penetration of the toothed lock washer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]In the drawings are depicted exemplary embodiments of the invention,
which will be described in the following, and wherein;

[0020]FIG. 1 illustrates an overall view of a seat belt retractor and
pretensioning device in accordance with the present invention,

[0023]FIG. 4 illustrates the latching plane of the seat belt retractor in
accordance with this invention shown in section, and

[0024]FIG. 5 illustrates an exemplary embodiment of the belt shaft with an
axial locking device in section view.

DETAILED DESCRIPTION OF THE INVENTION

[0025]The seat belt retractor and a pretensioning device 10 in accordance
with this invention, which can be seen in FIG. 1, the seat belt retractor
consists of a U-shaped seat belt retractor housing 11, in whose housing
legs 12 a belt spool or shaft 13 is mounted, on which a belt webbing 14
is wound. A belt buckle 15 is mounted on the free end of the belt webbing
14, into which or from which a locking tongue 16 can be inserted or
detached, wherein the locking latch plate tongue 16 is mounted on a seat
belt 17. Seat belt arrangements such as that described above are known.
In order to be able to subject the belt buckle 15 to a tightening by
winding up the belt webbing 14 on the belt shaft 13, a pretensioning
device 18 is fastened on a housing leg 12 consisting of a pretensioner
tube 19 and a gas generator receptacle 20. The connection between the
pretensioning device 18 and the belt shaft 13 is carried out by means of
a drive wire or cable 22, which is wound on a shaft extension 24 of the
belt shaft 13 and its end is affixed to the shaft.

[0026]As can also be seen in FIG. 2, the end of the drive cable 22
attached to the pretensioning device 18 is guided into the pretensioner
tube 19 and is connected herein to a piston 21, which can move within the
tightening tube 19. A gas generator 23 is arranged in the gas generator
receptacle 20 of the pretensioner tube 19, which upon activation releases
gas, which drives the piston 21 in the pretensioner tube 19, so that the
drive cable 22 is unwound from the shaft extension 24 of the belt shaft
13 and consequently causes the belt shaft 13 to rotate which tightens or
pretensions webbing 14.

[0027]The belt shaft 13 has a shaft element 25, which has a hollow
configuration, on which the belt webbing 14 is wound. A locking element
27, which passes with at least one tooth through a passage opening 28
arranged in the shaft element 25, is arranged within the plane of the
housing leg 12 in the shaft element 25, through which passes the shaft
extension 24. A sleeve 26 on whose outer circumference the drive cable 22
is wound, is slid on the shaft extension 24, which overlaps the shaft
extension 24 in order to enlarge the tightening radius. The sleeve 26 has
an opening 29 for the passage of the locking element 27, which is flush
with the passage opening 28 of the shaft element 25, so that the locking
element engages with the allocated gearing of the housing leg 12 when it
is pivoted out into its locking position. As is not shown in detail, the
locking element 27, according to the description of DE 103 04 943 B3,
which is herewith also being made into an object of the present
disclosure, is pretensioned by a spring element into its pivoted out
locking position, so that the locking element 27 ratchets away over the
gearing of the housing leg 12 when the belt shaft 13 is rotated, and
brings about the immediate locking of the belt shaft 13 in the belt
withdrawal direction when the belt shaft 13 is rotated after the
pretensioning rotation has ended.

[0028]As can be inferred in more detail from FIG. 3, the sleeve 26 is
axially and radially fixedly mounted on the shaft element 25, in that
projections 30 are stamped in the plane of the shaft element 25, which
project from the sleeve 26 radially inwardly, which in turn engage into
recesses 31 formed in the sleeve 26. Two diametrically opposite
projections 30 engaging with recesses 31 are represented in the shown
exemplary embodiment, in which the projections 30 are aligned inclined in
the axial direction of the shaft element 25 in such a way that their
longitudinal axis intersects the longitudinal axis of the shaft element
25. The mutually opposite projections 30 are preferably arranged therein
with an opposite oriented inclination, so that the sleeve 26 is axially
and radially immovably fixed on the shaft element 25. In FIG. 3 can
furthermore be seen a cable end fitting or bushing 32 for the drive cable
22, which in the shown exemplary embodiment is positioned in the interior
of the shaft element 25, so that the drive cable 22 runs toward its outer
circumference through a corresponding clearance in the sleeve 26.

[0029]In FIG. 4 can finally be seen the arrangement and mounting of the
locking element 27 in the hollow shaft element 25, which corresponds to
the description in the representative DE 103 04 943 B3. Here, the locking
element 27, which is mounted with a bearing arrangement 35 in a
perforation 36 formed in the shaft element 25 as well as in the sleeve
26, respectively, is supported when engaged with the gearing 37 of the
allocated housing leg 12, on an edge region of the opening 29 of the
sleeve 26, which is configured as an inwardly curved nose 33 that engages
in a pocket 34 formed in the locking element 27. Consequently, the
introduction of the bracing force is carried out, on the one hand, into
the sleeve 26, and on the other hand, via the bearing attachment 35 into
the sleeve 26 as well as into the shaft element 25.

[0030]As can be seen in FIG. 5, the axial locking device of the belt shaft
13 is positioned on the housing leg 12 that interacts with the locking
element 27, and namely through an internal retaining element 41 slid on
the shaft element 25, which is configured, with the exception of the
passage opening 28, with a closed circumference. The internal retaining
element 41 is located in the interior of the housing frame 11 between the
housing legs 12 and is configured as a closed retaining ring, which is
supported on a stop 42 configured by stamping or forming of the shaft
element 25. The sleeve 26, on whose outer circumference the drive cable
22 is wound, is slid on the outside of the shaft extension 24, which
projects beyond the housing leg 12. The drive element, which is provided
at its end with a cable fitting 44, is guided into the interior of the
shaft element through an opening 43 formed in the sleeve 26 as well as in
the shaft element 25 and is fixed by means of the cable fitting 44. Due
to this configuration, the cable fitting 44 together with the drive cable
22 extending from it acts at the same time as an anti-sliding safety for
the external sleeve 26, so that after the installation is complete, the
sleeve is immovably fixed on the shaft element 25.

[0031]In order to reduce friction losses during the rotation of the belt
shaft 13, the internal retaining element 41 as well as the external
sleeve 26 are provided with a radial facet 45 which respectively face the
housing leg 12, so that a basically linear installation of the two
retaining elements 41 or 26 on the housing leg 12 is achieved. Here, the
facet 45 is formed in such a way that the passage opening 28, which is
configured in the shaft element 25 to allow the passage of the locking
element 27, is bridged in each case.

[0032]The features of object of these documents, which are disclosed in
the previous description, the patent claims, the abstract, and the
drawings, can be essential individually and also in any desired
combinations for the realization of the invention in its various
embodiments.